Additives comprising fractions of a percent to several percent of solid propellant mixtures have been considered through the years and are commonly employed in many rocket propellant and explosive compositions. Various additives include burn-rate modifiers (e.g., ferric oxide, metal oxides, and organometallics), curing agents, and plasticizers. In certain cases, additions of small (e.g., <5% by weight) amounts of powdered material to the propellant mixture have been shown to increase or otherwise favorably modify the burn rate. Nanoparticle additives may have an even further influence on the burn rate because of their high surface-to-volume ratios.
One known solution-phase synthesis of titania nanoparticles is the sol-gel method, in which an organometallic titanium precursor such as a titanium tetraalkoxide is reacted with water to form a suspension of titania nanoparticles, which is then dried to form a powder. Such titania powders produced by this method act as catalysts to increase the burning rate of composite solid propellants. In the current state of the art, the titania nanoparticles are incorporated into the composite propellant by mechanically mixing the powder with a polymer binder, such as hydroxyl-terminated polybutadiene (HTPB).